U.S. patent number 5,211,959 [Application Number 07/637,533] was granted by the patent office on 1993-05-18 for processes for producing slow-release powders.
This patent grant is currently assigned to Japan Atomic Energy Research Institute. Invention is credited to Isao Ishigaki, Keizo Makuuchi, Fumio Yoshii.
United States Patent |
5,211,959 |
Yoshii , et al. |
May 18, 1993 |
Processes for producing slow-release powders
Abstract
A process for producing a slow-release powder which permit
various active ingredients such as perfumes, insect control agents,
rust inhibitors, mold inhibitors and antibacterial agents to be
slowly released over a prolonged time, the process comprising the
steps of mixing a long-chain compound with the ingredients, mixing
the resulting mixture with urea, and exposing the resulting urea
adduct to radiation.
Inventors: |
Yoshii; Fumio (Gunma,
JP), Makuuchi; Keizo (Gunma, JP), Ishigaki;
Isao (Gunma, JP) |
Assignee: |
Japan Atomic Energy Research
Institute (Tokyo, JP)
|
Family
ID: |
27454043 |
Appl.
No.: |
07/637,533 |
Filed: |
January 4, 1991 |
Foreign Application Priority Data
|
|
|
|
|
Jan 11, 1990 [JP] |
|
|
2-4237 |
Feb 3, 1990 [JP] |
|
|
2-25013 |
May 24, 1990 [JP] |
|
|
2-134976 |
May 24, 1990 [JP] |
|
|
2-134977 |
|
Current U.S.
Class: |
424/489; 424/409;
424/501; 424/502; 514/772.6; 522/184; 522/186; 522/78; 522/911;
522/912; 523/102; 523/122; 523/300 |
Current CPC
Class: |
A01N
25/08 (20130101); A61K 8/42 (20130101); A61K
8/8152 (20130101); A61L 9/042 (20130101); A61L
9/044 (20130101); A61Q 13/00 (20130101); A61K
2800/56 (20130101); Y10S 522/911 (20130101); Y10S
522/912 (20130101) |
Current International
Class: |
A01N
25/08 (20060101); A61L 9/04 (20060101); A61K
009/14 (); A61K 007/46 (); A61K 047/32 (); C08F
002/54 () |
Field of
Search: |
;424/489,501,502,409,81
;523/300,102,122 ;522/184,186,78,911,912 ;514/772.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Page; Thurman K.
Assistant Examiner: Webman; E. J.
Attorney, Agent or Firm: Banner, Birch, McKie &
Beckett
Claims
What is claimed is:
1. A process for producing a slow release powder by the steps
of:
first mixing a long-chain compound and a slow-releasable substance,
wherein the weight ratio of said long-chain compound to said
slow-releasable substance ranges from 1:0.1 to 1:10; and
then mixing the resulting mixture with urea at a temperature
ranging from 20.degree. to 80.degree. C., wherein the molar ratio
of said urea to said long-chain compound ranges from 1:5 to
1:15,
wherein said long-chain compound has a molecular weight of at least
100, said long-chain compound facilitating the incorporation of
said slow-releasable substance into said urea to form a urea
adduct, wherein said long chain compound is selected from the group
consisting of hexyl alcohol, n-octyl alcohol, nonyl alcohol, decyl
alcohol, undecyl alcohol, lauryl alcohol, n-capric acid, caproic
acid, lauric acid, oleic acid, linoleic acid, stearic acid,
1,6-hexanediol diacrylate, 1,6-hexanediol monoacrylate, lauryl
acrylate, stearyl acrylate and caprolactone modified 2-hydroxyethyl
acrylate, and
wherein the slow-releasable substance is selected from the group
consisting of a natural perfume, a synthetic perfume, an insect
control agent, an insect killing agent, a rust inhibitor, a mold
inhibitor and an antibacterial agent.
2. A process for producing a slow release powder by the steps
of:
mixing a long chain compound with a slow-releasable substance,
wherein the weight ratio of said long-chain compound to said
slow-releasable substance ranges from 1:0.1 to 1:10;
mixing the resulting mixture with urea at a temperature ranging
from 20.degree. to 80.degree. C., wherein the molar ratio of said
urea to said long-chain compound ranges from 1:5 to 1:15; and
exposing the resulting urea adduct to radiation, wherein the dose
of radiation ranges from 5 to 100 kGy,
wherein said long-chain compound has a molecular weight of at least
100 and is polymerizable upon exposure to radiation, said
long-chain compound facilitating the incorporation of said
slow-releasable substance into said urea to form a urea adduct,
wherein said long chain compound is selected from the group
consisting of oleic acid, linoleic acid, 1,6-hexanediol diacrylate,
1,6-hexanediol monoacrylate, lauryl acrylate, stearyl acrylate and
caprolactone modified 2-hydroxyethyl acrylate, and
wherein the slow-releasable substance is selected from the group
consisting of a natural perfume, a synthetic perfume, an insect
control agent, an insect killing agent, a rust inhibitor, a mold
inhibitor and an antibacterial agent.
3. A process according to claim 1 or 2 wherein said long-chain
compound is a mixture of two or more compounds.
4. A process according to claim 2 wherein said radiation is
gamma-rays, electron beams or X-rays.
Description
BACKGROUND OF THE INVENTION
This invention relates to processes for producing slow-release
powders. In one aspect, this invention provides a process for
producing a slow-release powder by first mixing a long-chain
compound with a slow-releasable substance and then mixing the
resulting mixture with urea. In another aspect, the invention
provides a process for producing a slow-release powder by first
mixing a long-chain compound with a slow-releasable substance, then
mixing the resulting mixture with urea, and finally exposing the
resulting urea adduct to radiation.
Slow-release powders permit various active ingredients such as
perfumes, insect control agents, rust inhibitors, mold inhibitors
and antibacterial agents to be slowly released over a prolonged
time, thereby expanding the application field of those substances.
The use of slow-release powders has been expanding these days as an
adjunct to improvements in the quality of national life.
Known clathrates (hereinafter sometimes referred to as "adducts")
capable of incorporating various substances include hydroquinone,
deoxycholic acid, perhydrotriphenylene and cyclodextrins. The
last-mentioned cyclodextrins form clathrates in powder form that
are fairly high in their ability to include substances. However, it
is not easy to form slow-release powders with cyclodextrins since
the steps of incorporating slow-releasable substances and drying
the mixture to obtain a powder are quite time-consuming.
Furthermore, compared to urea used in the present invention,
cyclodextrins are low in their ability to include substances and
yet they are expensive.
The present inventors conducted intensive studies in order to
develop an economical technique for producing slow-release powders
having longer life and, as a result, they have succeeded in
attaining this objective by using a mixture of urea and a
long-chain compound, which idea has not been conceived of in the
light of conventional clathrates including slow-releasable
substances.
SUMMARY OF THE INVENTION
The first object of the present invention is to provide an
economical and safe slow-release powder. More particularly, the
short life and high cost which are the two major disadvantages of
conventional slow-release powders can be eliminated by
incorporating a slow-releasable substance in an adduct of urea and
a long-chain compound. It is well known that urea forms adducts
with certain substances. However, urea mixed with a slow-releasable
substance does not form an adduct with the latter and the desired
slow-release powder cannot be obtained. As a result of their
continued studies, the present inventors found that a
slow-releasable substance could be incorporated in an adduct of
urea and a long-chain compound by a two-step process comprising the
steps of mixing the slow-releasable substance with the long-chain
compound and mixing the resulting mixture with urea. The present
invention has been accomplished on the basis of this finding.
The second object of the present invention is to provide a
slow-release powder that does not contain any residual long-chain
compound. The present inventors noted that long-chain compounds had
two double bonds (C.dbd.C) in their molecule that rendered them
highly polymerizable. The inventors therefore attempted to reduce
or eliminate those long-chain compounds by polymerization. As a
result of their continued studies, the inventors found that the
long-chain compounds in the adducts of urea and slow-releasable
substances readily polymerized by exposure to radiation. The second
aspect of the present invention has been accomplished on the basis
of this finding. The characteristic feature of this aspect lies in
first incorporating a slow-releasable substance in an adduct of
urea and a long-chain compound and then polymerizing the long-chain
compound by exposure to radiation.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described below in detail.
Long-Chain Compound
While various long-chain compounds can be used in the present
invention, those which have a molecular weight of at least 100 and
which have functional groups attached to a molecule comprising
oxyethylene or recurring methylene groups were found to be
particularly effective in allowing slow-releasable substances to be
incorporated into the crystal of urea. Such long-chain compounds
include: higher alcohols such as hexyl alcohol [CH.sub.3
(CH.sub.2).sub.5 OH], normal octyl alcohol [CH.sub.3
(CH.sub.2).sub.7 OH], nonyl alcohol [CH.sub.3 (CH.sub.2).sub.8 OH],
decyl alcohol [CH.sub.3 (CH.sub.2).sub.9 OH], undecyl alcohol
[CH.sub.3 (CH.sub.2).sub.10 OH] and lauryl alcohol [CH.sub.3
(CH.sub.2).sub.11 OH]; aliphatic acids such as normal capric acid
[CH.sub.3 (CH.sub.2).sub.8 COOH], caproic acid [CH.sub.3
(CH.sub.2).sub.4 COOH], lauric acid [CH.sub.3 (CH.sub.2).sub.10
COOH], oleic acid (C.sub.18 H.sub.34 O.sub.2), linoleic acid
(C.sub.18 H.sub.32 O.sub.2) and stearic acid [CH.sub.3
(CH.sub.2).sub.16 COOH]; and polymerizable monomers such as
1,6-hexanediol diacrylate, 1,6-hexanediol monoacrylate, lauryl
acrylate (C.sub.15 H.sub.28 O.sub.2), stearyl acrylate (CH.sub.2
--CHCOOC.sub.18 H.sub.23) and caprolactone modified 2-hydroxyethyl
acrylate (C.sub.11 H.sub.18 O.sub.5). Any other long-chain
compounds can be used to have various substances incorporated into
urea adducts as long as they have a comparatively small degree of
branching, have molecular weights of at least 100 and if they are
capable of forming adducts with urea.
Various slow-releasable substances can be used in the present
invention and typical examples are described below.
Natural and Synthetic Perfumes
Both natural and synthetic perfumes can be used in the present
invention and natural perfumes may be either animal or plant
derived such as lavender oil, citronella oil, rose oil, lemon oil
and jasmine oil. Various synthetic perfumes can also be used and
they include, for example, acetophenone (C.sub.8 H.sub.8 O), anisic
aldehyde (C.sub.8 H.sub.8 O.sub.2), anisole (C.sub.7 H.sub.8 O),
undecylenic aldehyde (C.sub.11 H.sub.20 O), isoamyl formate
(C.sub.6 H.sub.12 O.sub.2), geranyl formate (C.sub.11 H.sub.16
O.sub.2), isoamyl acetate (C.sub.7 H.sub.14 O.sub.2),
dimethylbenzylcarbinyl acetate (C.sub.12 H.sub.16 O.sub.2),
vanillin (C.sub.8 H.sub.8 O.sub.3), isoamyl propionate (C.sub.8
H.sub.16 O.sub.2), ethyl propionate (C.sub.5 H.sub.10 O.sub.2),
paramethyl acetophenone (C.sub.9 H.sub.10 O) and isoamyl butyrate
(C.sub.9 H.sub.18 O.sub.2). Other perfumes can also be used if they
are capable of forming adducts with urea in the presence of
long-chain compounds.
Insect Control and Insect Killing Agents
Insect control agents that can be used in the present invention are
those compounds which have insect control and killing effects, as
exemplified by p-dichlorobenzene, o-dichlorobenzene and dimethyl
phthalate. Other insect control and killing agents may of course be
employed if they are capable of forming adducts with urea in the
presence of long-chain compounds.
Rust Inhibitors
Rust inhibitors that can be used in the present invention include
aliphatic acids and metal soaps. Rust inhibiting oils can also be
used and they include spindle oils, turbine oils and cylinder oils.
Any other rust inhibitors and rust inhibiting oils can be used as
long as they are capable of forming adducts with urea in the
presence of long-chain compounds.
Mold Inhibitors and Bactericides
The mold inhibitors that can be used in the present invention
include those which have bacteriostatic and bactericidal effects
and may be exemplified by toluene,
5-ethoxy-3-trichloromethyl-1,2,4-thiadiazole,
1,4-dichloro-2,5-dimethoxybenzene, 2,6-dichloro-4-tetraaniline and
zinc ethylenebisdithiocarbonate. Other mold inhibitors having
bacteriostatic or bactericidal effects can also be used as long as
they are capable of forming adducts with urea in the presence of
long-chain compounds.
The two processes for producing slow-release powders according to
the present invention are described below. The first process
comprises the steps of mixing a long-chain compound with a
slow-releasable substance and mixing the resulting mixture with
urea. The second process comprises the steps mixing a long-chain
compound with a slow-releasable substance, mixing the resulting
mixture with urea, and exposing the resulting urea adduct to
radiation.
In either process, the ratio of the long-chain compound to the
slow-releasable substance ranges from 1:0.1 to 1:10 on a weight
basis. The exact value of this ratio will vary with the molecular
weight of the specific slow-releasable substance used and
slow-releasable substances having higher molecular weights will be
used in smaller proportions. If the proportion of the long-chain
compound is too low, incorporation of the slow-releasable substance
will become difficult to accomplish. If, on the other hand, the
proportion of the long-chain compound is excessive, the
concentration of the slow-releasable substance in the urea adduct
will be too low to produce a slow-release powder having
satisfactory performance.
The ratio of urea to the long-chain compound ranges from 1:5 to
1:15, preferably from 1:8 to 1:11, on a molar basis. If the
proportion of urea is too low, incorporation of the slow-releasable
substance becomes difficult to accomplish. If, on the other hand,
the proportion of urea is excessive, an increasing amount of urea
will remain unreacted to form an adduct with the long-chain
compound, which is by no means economical.
No special method of addition is required to perform the first step
of mixing the slow-releasable substance with the long-chain
compound. If the slow-releasable substance is liquid, the
long-chain compound need be dissolved in said substance. If the
slow-releasable substance is solid, it may be heated or otherwise
treated to increase its solubility and is then dissolved in the
long-chain compound.
The second step of mixing the (liquid) mixture of the
slow-releasable substance and the long-chain compound with urea can
also be performed without requiring any special technique and said
liquid may be gently mixed with urea under agitation as it is
sprayed with the liquid. When mixed under agitation, urea will
first absorb the liquid to form a paste and increase in volume.
When the paste sample is left to stand, it gradually decreases in
volume to turn to a freely flowing powder, or the intended
slow-release powder of the present invention. The second step will
be completed within a period of from about 2 to 20 hours. The
agitation is effected at a temperature of 20.degree.-80.degree. C.,
preferably at 30.degree.-60.degree. C. If the temperature for
agitation exceeds 80.degree. C., the urea adduct will decompose.
The atmosphere for agitation is not limited in any particular way
but the use of a closed vessel is preferred in order to avoid
dissipation of the slow-releasable substance.
The slow-release powder obtained by the process of the present
invention may be formulated by common techniques in the art and
various slow-release powder product can be produced by any known
methods.
The polymerization reaction initiated by exposure to radiation is
the third step of the process according to the second aspect of the
present invention is carried out in order to render the long-chain
compound in the slow-release powder harmless by radiation-initiated
polymerization. In this third step, the adduct of urea and the
long-chain compound which has the slow-releasable substance
incorporated therein is polymerized by irradiation in a closed
vessel. If the proportion of the slow-releasable substance in the
urea adduct is comparatively low, the long-chain compound is very
reactive as to polymerize merely by irradiation. If, on the other
hand, the concentration of the slow-releasable substance in the
urea adduct is high, the long-chain compound is not sufficiently
reactive to have the intended reaction proceed to the fullest
extent. In this case, the urea adduct is heated to generate an
active species, which is utilized to polymerize the long-chain
compound. Radiations that can be used to perform the third step
include gamma-rays, electron beams, X-rays and any other kinds of
radiations that may be used on an industrial basis. The dose of
radiation ranges from 5 to 100 kGy, preferably from 20 to 60 kGy.
If the dose of radiation is too small, the long-chain compound may
not be completely polymerized. If the dose of radiation is
excessive, the slow-releasable substance may be decomposed by
radiation. If necessary, the adduct exposed to radiation may be
heated at 40.degree.-70.degree. C., preferably at 50.degree. C. If
the heating temperature exceeds 70.degree. C., the adduct can
potentially decompose. No special method is required to implement
irradiation, but irradiation in an inert atmosphere using a closed
vessel is preferred.
The present invention is described below in greater detail with
reference to examples and comparative examples.
EXAMPLE 1
A slow-release powder of an insect control agent, o-dichlorobenzene
(o-DCB) was prepared. When used alone, o-DCB will not form a
clathrate with urea but it can be incorporated into a urea adduct
in the presence of a long-chain compound.
When 4 g of urea was mixed under agitation with a liquid mixture of
1.4 g of oleic acid as a long-chain compound and 0.48 g of o-DCB,
the mixture first took on a paste form but upon standing, the paste
turned to a free-flowing powder in about 10 hours, which was a
slow-release powder incorporating the insect control agent. A
slow-release test was conducted by measuring the amount of residual
o-DCB incorporated in the powder at predetermined time intervals of
heating at 50.degree. C. As a comparison, a mixture of o-DCB (0.48
g) and urea (4 g) that was formed in the absence of a long-chain
compound was heated at 50.degree. C. and the amount of residual
o-DCB was measured at predetermined time intervals. In the
comparison, the mixture had the liquid o-DCB adhering to the solid
crystal of urea. The long-chain compound was not released at all
from the slow-release powder and only o-DCB was slowly released
from the powder. The test results are shown in the following table,
from which one can clearly see that in the presence of the
long-chain compound, a slow-release powder was successfully
obtained that had o-DCB incorporated into the urea adduct. It took
as many as two days for substantially all of the o-DCB to be
released from the slow-release powder.
______________________________________ Example 1 Comparative
Example 1 Time (hr) Slow-release powder Mixture of urea and o-DCB
______________________________________ 4 83% 70% 8 65 43 24 21 0
______________________________________
EXAMPLE 2
A slow-release powder of a mold inhibitor, toluene, was prepared.
As in Example 1, toluene used alone did not form an adduct with
urea but when urea was added to a mixture of toluene with a
long-chain compound, a slow-release compound incorporating toluene
could be formed. Stated more specifically, 4 g of hexanediol
diacrylate as urea was added to a liquid mixture of 1.47 g of a
long-chain compound and 0.6 g of toluene and by agitation and
subsequent standing for about 10 hours, a free-flowing slow-release
powder incorporating toluene formed. As a comparison, a mixture of
0.6 g of toluene and 4 g of urea was formed in the absence of a
long-chain compound and the amount of residual toluene was measured
at predetermined time intervals of heating at 50.degree. C. The
test results are shown in the following table, from which one can
clearly see that a slow-release powder having toluene incorporated
in a urea adduct could be obtained in the presence of a long-chain
compound.
______________________________________ Example 2 Comparative
Example 2 Time (hr) Slow-release powder Mixture of urea and toluene
______________________________________ 4 70% 56% 8 58 42 24 26 0
______________________________________
EXAMPLE 3
A slow-release powder was prepared using a synthetic perfume giving
off the fragrance of chewing gum and having a molecular weight of
ca. 100. As in Example 1, the perfume used alone did not form an
adduct with urea but in the presence of hexanediol diacrylate as a
long-chain compound, the perfume formed an adduct with urea,
thereby producing a slow-release powder of the perfume. Stated more
specifically, 8.0 g of urea was added to a liquid mixture of 0.82 g
of the perfume and 1.85 g of the long-chain compound and by
agitation and subsequent standing for about 5 hours, the mixture
which was initially in a paste form gradually turned to a
slow-release powder incorporating the perfume. Upon standing at
room temperature, the powder retained the fragrance of the perfume
for at least 3 months.
EXAMPLE 4
A slow-release powder was prepared using a perfume giving off the
fragrance of pine resin and having a molecular weight of ca. 130.
In this example, too, the perfume used. alone did not form an
adduct with urea but in the presence of hexanediol diacrylate as a
long-chain compound, the perfume formed an adduct with urea. Stated
more specifically, 8 g of urea was added to a liquid mixture of
1.85 g of a long-chain compound and 0.82 g of the perfume and by
agitation and subsequent standing for about 5 hours, the mixture
which was initially in a paste form gradually turned to a
slow-release powder incorporating the perfume. The resulting urea
adduct gave off the fragrance of pine resin that lasted for at
least 3 months.
The results of Examples 1-4 clearly show that a slow-release powder
having a slow-releasable substance incorporated into a urea adduct
could be formed in the presence of a long-chain compound.
EXAMPLE 5
A slow-release powder was prepared using a synthetic perfume,
isobutyl acetate (IBA). When used alone, IBA will not form a
clathrate with urea but it can be incorporated into a urea adduct
in the presence of oleic acid as a long-chain compound.
When 6 g of urea was mixed under agitation with a liquid mixture of
1.89 g of oleic acid and 0.78 g of IBA, the mixture first took on a
slurry form but upon standing for ca. 5 hours, the slurry turned to
a free-flowing powder, which was a slow-release powder
incorporating the perfume IBA. A slow-release test was conducted by
gravimetric measurements of the amount of residual IBA incorporated
in the powder at predetermined time intervals of standing at room
temperature. As a comparison, a mixture of IBA (0.78 g) and urea (6
g) that was formed in the absence of oleic acid was left to stand
at room temperature and the amount of residual IBA was measured at
predetermined time intervals. In the comparison, the mixture had
the perfume IBA adhering to the solid crystal of urea. Oleic acid
was not released at all from the slow-release powder and only IBA
was slowly released from the powder. The test results are shown in
the following table, from which one can clearly see that in the
presence of oleic acid, a slow-release powder was successfully
obtained that had IBA incorporated into the urea adduct.
______________________________________ Example Comparative Example
5 Time (hr) Slow-release powder Mixture of urea and IBA
______________________________________ 5 87.7% 83.4% 27 51.1 29.9
45 30.2 0 67 16.6 ______________________________________
EXAMPLE 6
Using lauryl acrylate as a long-chain compound, a urea adduct
having a synthetic perfume IBA incorporated into the urea crystal
was prepared as in Example 5 and the resulting urea adduct was
subjected to a slow-release test as in Example 5. Lauryl acrylate
was used in an amount of 1.61 g. When the liquid mixture of lauryl
acrylate and IBA was mixed with urea under agitation, the mixture
which was initially in the form of slurry gradually turned to a
powder upon standing for ca. 10 hours. The test results clearly
show that in the presence of lauryl acrylate, IBA was incorporated
into the urea adduct to form a slow-release powder.
______________________________________ Example 6 Comparative
Example 6 Time (hr) Slow-release powder Mixture of urea and IBA
______________________________________ 5 83.1% 89.6% 27 39.4 29.0
45 22.2 0 67 20.1 ______________________________________
EXAMPLE 7
Using caprolactone-modified 2-hydroxyl acrylate (trade name, Alonix
154) as a long-chain compound, a synthetic perfume IBA was
incorporated into a urea adduct. The preparation of the urea adduct
and the testing of its ability to release IBA were conducted as in
Example 5. Alonix 154 was used in an amount of 1.54 g. As in
Example 5, the mixture of urea with the liquid mixture of Alonix
154 and IBA was initially in a slurry form but as it was agitated
and left to stand over time, the mixture turned into a slow-release
powder having IBA incorporated into the urea adduct. The slow
release of IBA demonstrates its incorporation in the urea adduct.
There was no detectable release of Alonix 154 from the powder.
______________________________________ Example 7 Comparative
Example 7 Time (hr) Slow-release powder Mixture of urea and IBA
______________________________________ 5 88.7% 89.6% 27 55.5 29.9
45 35.8 0 67 27.5 ______________________________________
EXAMPLE 8
A slow-release powder was prepared using a synthetic perfume,
isobutyl acetate (IBA), that was incorporated in an adduct of urea
and a polymer. When used alone, IBA will not form an adduct with
urea but it can be incorporated into a urea adduct in the presence
of hexanediol diacrylate as a long-chain compound.
A long-chain compound (1.47 g) and IBA (0.75 g) were mixed and the
resulting mixture was sprayed on 5.6 g of urea. The mixture was
then left to stand overnight at 25.degree. C. to form the powder of
a urea adduct having IBA incorporated in the long-chain compound.
The adduct was irradiated with gamma-rays for a dose of 50 kGy and
heated at 50.degree. C. for 15 minutes to polymerize the long-chain
monomer in the adduct, whereby a slow-release powder was obtained
that consisted of the urea adduct having the synthetic perfume
incorporated in the adduct of urea and the polymer of the
long-chain compound. The thus obtained slow-release powder was
tested for its ability to slowly release the synthetic perfume. As
a comparison, 1.47 g of the long-chain compound and 0.75 g of IBA
were mixed and the resulting mixture was sprayed on 5.6 g of urea
and, after leaving the mixture to stand overnight at 25.degree. C.,
the resulting urea adduct having IBA incorporated in the long-chain
compound was checked for its ability to slowly release IBA without
irradiation with gamma-rays. The slow release of IBA from the urea
adduct was determined by gravimetric measurements of IBA release at
predetermined time intervals of standing in a 50-ml open weighing
bottle at 25.degree. C. The results of measurements indicate the
amounts of residual perfume in the adduct. In the tests, the
long-chain compound was not at all found to be released from the
adduct. The test results are shown in the following table, from
which one can clearly see that the slow releasability of IBA from
the unirradiated adduct was completely retained even after the
adduct was irradiated with gamma-rays to polymerize the long-chain
compound in the adduct. Thus, the adduct of urea and long-chain
compound which incorporated the synthetic perfume turned to a
slow-release powder of urea and polymer upon exposure to
radiation.
______________________________________ Example 8 Comparative
Example 8 Time (hr) After irradiation Before irradiation
______________________________________ 8 79.0% 77.0% 24 59.7 56.7
48 28.5 28.7 67 25.4 23.4
______________________________________
EXAMPLE 9
A slow-release powder was prepared from an insect control agent,
o-dichlorobenzene (o-DCB) that was incorporated into an adduct of
urea and a polymer. Like the IBA used in Example 8, o-DCB when used
alone did not form an adduct with urea but in the presence of
hexanediol diacrylate as a long-chain compound, o-DCB could be
incorporated into a urea adduct. To state more specifically, 4 g of
urea was added to a liquid mixture of a long-chain compound (1.47
g) and o-DCB (0.48 g) and by thorough stirring and subsequent
standing overnight, the mixture turned into a free-flowing powder
of the adduct of urea and the long-chain compound. When this powder
was irradiated with gamma-rays for a dose of 60 kGy, the long-chain
compound in the urea adduct polymerized to yield a product having
the insect control agent incorporated in the adduct of urea and the
polymer of the long-chain compound. As a comparison, an
unirradiated adduct of urea and a long-chain compound was prepared
that had the insect control agent incorporated therein. A
slow-release test was conducted by determining the amount of
residual o-DCB incorporated into the adduct at predetermined time
intervals of heating at 50.degree. C. in an open weighing bottle.
The test results are shown in the following table, from which one
can clearly see that the slow-release speed of the long-chain
compound in the irradiated adduct was substantially the same
irrespective of whether said compound was radiation-polymerized or
not. It took 48 hours for substantially all of the o-DCB to be
released from the adduct. Hence, the long-chain compound
polymerized by irradiation successfully yielded a powder of the
urea-polymer adduct which had the insect control agent incorporated
therein.
______________________________________ Example 9 Comparative
Example 9 Time (hr) After irradiation Before irradiation
______________________________________ 6 76.1% 73.2% 22 27.3 38.3
30 16.3 23.6 ______________________________________
EXAMPLE 10
A slow-release powder was prepared using an adduct of urea and a
polymer which had a synthetic perfume incorporated therein that
gave off the fragrance of chewing gum and that had a molecular
weight of ca. 100. In this example, too, the synthetic perfume used
alone did not form an adduct with urea but in the presence of
hexanediol diacrylate as a long-chain compound, the perfume
successfully formed an adduct with urea to form a slow-release
powder. When the long-chain compound was polymerized by exposure to
radiation, a more harmless slow-release powder was obtained that
had the synthetic perfume incorporated in the adduct of urea and
the polymer of the long-chain compound. To state more specifically,
8.0 g of urea was added to a liquid mixture of 1.85 g of the
long-chain compound and 0.82 g of the perfume and by agitation and
subsequent standing for ca. 5 hours, the mixture which was
initially in a paste form gradually turned into a powder, thus
yielding an adduct of urea and the long-chain compound that had the
perfume incorporated therein. When this adduct was irradiated with
gamma-rays for a dose of 50 kGy, the long-chain compound in the
adduct polymerized to produce a slow-release powder having the
synthetic perfume incorporated in the adduct of urea and the
polymer of the long-chain compound. This slow-release powder
permitted the contained perfume to sustain its fragrance for a
period of at least 3 months when it is left at room temperature. It
was therefore clear that the slow releasability of the perfume
remained the same even when the long-chain compound in the urea
adduct was polymerized by irradiation.
EXAMPLE 11
A slow-release powder was prepared using an adduct of urea and a
polymer which had a perfume incorporated therein that gave off the
fragrance of pine resin and that had a molecular weight of ca. 130.
In this example, too, the perfume used alone did not form an adduct
with urea but in the presence of hexanediol diacrylate as a
long-chain compound, the perfume successfully formed an adduct with
urea. To render the long-chain compound harmless, the adduct of
urea and the long-chain compound harmless, the adduct of urea and
the long-chain compound which had the pine resin perfume
incorporated therein was exposed to radiation. To state more
specifically, 8 g of urea was added to a liquid mixture of 1.85 g
of the long-chain compound and 0.82 g of the perfume and by
agitation and subsequent standing for ca. 5 hours, the mixture
which was initially in a paste form gradually turned into a powder,
thus yielding an adduct of urea and the long-chain compound that
had the perfume incorporated therein. When this adduct was
irradiated with gamma-rays for a dose of 50 kGy, the long-chain
compound in the adduct polymerized to produce a slow-release powder
having the perfume incorporated in the adduct of urea and the
polymer of the long-chain compound. This slow-release powder
permitted the contained perfume to sustain its fragrance of pine
resin for a period of at least 3 months.
EXAMPLE 12
A slow-release powder was prepared using an adduct of urea and a
polymer which had a synthetic perfume, isobutyl acetate (IBA)
incorporated therein. When used alone, IBA will not form an adduct
with urea but it can be incorporated into a urea adduct in the
presence of lauryl acrylate.
Lauryl acrylate (1.61 g) and IBA (0.78 g) were mixed and the
resulting liquid mixture was sprayed on 6 g of urea. The mixture
was then left to stand at room temperature, whereupon a
slow-release powder was obtained that had IBA incorporated in a
urea adduct. The adduct was irradiated with gamma-rays for a dose
of 100 kGy to polymerize the lauryl acrylate in the adduct, whereby
a slow-release powder was obtained from the adduct having the
synthetic perfume incorporated in the adduct of urea and the
polymer of lauryl acrylate. The thus obtained slow-release powder
was tested for its ability to slowly release the synthetic perfume.
As a comparison, 1.61 g of lauryl acrylate and 0.78 g of IBA were
mixed and the resulting liquid mixture was sprayed on 6 g of urea
and, after leaving the mixture to stand overnight at room
temperature, the resulting urea adduct having IBA incorporated in
lauryl acrylate was checked for its ability to slowly release IBA
without irradiation with gamma-rays. The slow-release test was
conducted in the same way as in Example 8. In the test, lauryl
acrylate was not at all found to be released from the adduct. The
test results are shown in the following table, from which one can
clearly see that the slow releasability of IBA from the
unirradiated adduct was completely retained even after the adduct
was irradiated with gamma-rays to polymerize lauryl acrylate in the
adduct. Thus, the adduct of urea and lauryl acrylate which
incorporated the synthetic perfume turned to a slow-release powder
of urea and polymer upon exposure to radiation.
______________________________________ Example 12 Comparative
Example 12 Time (hr) After irradiation Before irradiation
______________________________________ 20 64.8% 58.25 42 40.6 32.0
72 25.1 25.0 ______________________________________
EXAMPLE 13
Using 2-hydroxyethyl acrylate monomer [CH.sub.2 .dbd.CHCOOCH.sub.2
CH.sub.2 OCO(CH.sub.2).sub.5 OH], a synthetic perfume, isobutyl
acrylate (IBA), was incorporated into a urea adduct to produce a
slow-release powder.
A liquid mixture of 2-hydroxyethyl acrylate monomer (1.54 g) and
IBA (0.78 g) was sprayed on 6 g of urea and, after thorough
agitation and subsequent standing at room temperature, the
resulting mixture was left to stand overnight, whereupon a
slow-release powder was obtained that had IBA incorporated in the
monomer in a urea adduct. The adduct was irradiated with gamma-rays
for a dose of 100 kGy to polymerize the monomer, whereby a
slow-release powder was obtained from the adduct having the perfume
incorporated in the adduct of a urea and the polymer. The thus
obtained slow-release powder was tested for its ability to slowly
release the perfume. As a comparison, a liquid mixture of
2-hydroxyethyl acrylate monomer (1.54 g) and IBA (0.78 g) was
sprayed on urea and the resulting mixture was thoroughly agitated.
After leaving the mixture to stand overnight, the resulting urea
adduct having IBA incorporated in the monomer was checked for its
ability to slowly release IBA without irradiation with gamma-rays.
The slow-release test was conducted in the same way as in Example
8. In the test, the monomer was not at all found to be released
from the adduct. The test results are shown in the following table,
from which one can clearly see that the slow releasability of IBA
from the unirradiated adduct did not vary greatly even when the
adduct was irradiated with gamma-rays to polymerize the monomer in
the adduct. Thus, the adduct of urea and monomer which incorporated
the synthetic perfume turned to a slow-release powder of urea and
polymer upon exposure to radiation.
______________________________________ Example 13 Comparative
Example 13 Time (hr) After irradiation Before irradiation
______________________________________ 20 61.7% 71.9% 42 35.0 40.6
72 25.2 28.9 ______________________________________
* * * * *